Clay Montgomery on Zero spin Si, page-9

Both post from Clay on X

There's more to the Silicon-28 story than just Quantum Computing. A lot more!The Silicon-28 isotope has a unique property, zero quantum spin. What does that mean?Silicon-28 atoms have the same number of protons as neutrons (14 of each). Since protons spin one way and neutrons spin the other, balancing them makes their total quantum spin, zero. But, natural silicon also contains the 29 isotope and that extra neutron destroys the spin-balance of the atoms. So, the silicon has to be purified (enriched) to remove the silicon-29 atoms.A big problem with QC is that these devices must be cooled to liquid helium temperatures. But, using zero-spin silicon makes it possible for QC transistors (qubits) to function at higher temperatures. Silicon also happens to be the easiest element from which to make transistors, at scale. Conventional transistors ignore the spins and manipulate electrons, instead, but that limits how small they can be made.There are huge advantages to making transistors that switch spins rather than electrons. The first one being the quantum property of entanglement. The chip industry is still trying to figure out how to package and merchandise that.But, Silicon-28 has another feature that can solve the biggest problem facing conventional (electron) transistors now, heat. Silicon-28 is a much better thermal conductor than 29. So, it also makes better conventional transistors! Who knew?So, chip companies are quietly looking for potential suppliers of Silicon-28, and not just for quantum computing.Purified Silicon-28 has been around for awhile, but the only source is Russia. It's produced by spinning silicon tetrafluoride gas (SiF4) in centrifuges, similar to how uranium is enriched.The Ukraine war disrupted the supply of Silicon-28, just as demand increased. So, there are now at least 2 start-ups racing to get into production ASAP, using the same laser enrichment technology as for uranium. The differences are the laser frequencies and the carrier gas is silane (SiH4) instead of UF6. The use of silane also has advantages over silicon tetrafluoride.Silex has a Silicon-28 process called Zero-Spin Silicon (ZS-Si) that uses a variant of their uranium enrichment technology, through their partners, Silicon Quantum Computing and UNSW Sydney.